The invention relates to a sley apparatus having a sley profile, a reed, and a drive. The sley profile carries the reed and is in active connection with the drive.
Jet weaving machines are characterized in particular in that the insertion of a weft thread into a shed is accomplished with the help of a flowing fluid, such as e.g. in air jet weaving machines with the help of compressed air. In a jet weaving machine of this kind a sley apparatus comprises a sley profile, a reed and a drive, with the sley profile carrying the reed and at least one apparatus which is designated as the main nozzle, and with the sley profile being in active connection with the drive. In this the weft thread is drawn off from a thread supply, which can for example be designed in the form of a drum storage, and accelerated for insertion into the shed by means of the main nozzle, which is fed by the flowing fluid. Additional air nozzles, so-called relay nozzles, which assist the progressing insertion of the weft thread into the shed, are provided at specific spacings along the weft insertion length on the sley profile. In this the main nozzle is in a rotationally fixed connection with the sley profile in order that the progressing weft insertion along the relay nozzles through the shed is not impaired by the pendulum-like movement of the sley apparatus. As a rule, the weft thread is held taut after its arrival until the shed is closed.
Under certain circumstances it proves advantageous to use a so-called tandem nozzle for the weft insertion in addition to the above-mentioned main nozzle. The tandem nozzle is placed in series ahead of the main nozzle. This arrangement corresponds substantially to two main nozzles which are placed one after the other with the purpose of achieving the introduction of the force for the thread transport via an increase of the thread surface on which the air acts. In this the tandem nozzle mainly takes over the unwinding of the weft thread from the drum storage, through which the unwinding resistance is compensated. Through this the pressure at the main nozzle can be diminished, which results in a more careful insertion of the web.
On the other hand, with a constant or higher pressure level of the main nozzle, the weft insertion speed or weft insertion time respectively can be varied in such a manner that depending on the weft material to be inserted and the weft thread length, i.e. the cloth draw-in width, a maximum weft-meter performance can be realized with the highest demands on the cloth quality.
Essentially two variants are known for the re-equipping of the sley profile from one main nozzle to a combination of a main nozzle with an additional tandem nozzle as a pre-nozzle. Either the tandem nozzle is fixedly connected to the frame of the weaving machine in a stationary manner by means of a holder section, or in this case the main nozzle is moved relative to the tandem nozzle during the weaving process. However, undesirable thread deflection points necessarily result with corresponding friction and the accompanying effects. In addition to this a second variant with a longer sley profile permits the reception of the main nozzle and the tandem nozzle. In this case there results a massive problem during the change back to only one main nozzle. Then, namely, in operation without the tandem nozzle, an additional unnecessary mass of the unused section of the sley profile must be co-moved, which can become highly problematical in particular at higher speeds of rotation of the machine.
The prior art for the arrangement of the main nozzle and the tandem nozzle on the sley profile will be explained in more detail in the following with reference to FIGS. 1 to 3 on the basis of several examples. To distinguish the prior art from the sley apparatus in accordance with the invention, the reference symbols in FIGS. 1 to 3 are provided with primes.
FIG. 1 shows a tandem nozzle 8xe2x80x2, which is connected stationarily to a holder profile part 5xe2x80x2. In this the holder profile part 5xe2x80x2 is in turn firmly connected to the frame 5xe2x80x3 of the weaving machine. Since the sley profile 1xe2x80x2 with the reed 2xe2x80x2 and the main nozzle 6xe2x80x2 carries out pendulum movements about the axis of the drive shaft 3xe2x80x2 in operation, for the purpose of beating up the weft thread, there necessarily result undesirable thread deflection points with the corresponding friction necessarily resulting between the stationary tandem nozzle 8xe2x80x2 and the main nozzle 6xe2x80x2, which is moved with the sley. This leads to the known negative accompanying phenomena such as the production of additional frictional heat and to increased mechanical tensions in the thread, which fluctuate strongly in magnitude. As a result the advantages, such as for example the reduction of the weft insertion time, i.e. increase in the weft insertion speed, which are achieved through the use of the tandem nozzle as a relieving pre-nozzle, are at least partly compensated again. In certain cases the negative accompanying phenomena as a result of the additional thread deflection points between the tandem nozzle and the main nozzle are so severe that in sum total the stresses on the weft thread even increase and therefore the use of a tandem nozzle as a pre-nozzle in a stationary arrangement cannot be allowed.
To avoid undesirable thread deflection points between the tandem nozzle 8xe2x80x2 and the main nozzle 6xe2x80x2 the pre-nozzle can likewise be mounted on the sley profile 1xe2x80x2 in accordance with FIG. 2. Then however the sley profile must be made longer. Admittedly additional thread deflection points between the tandem nozzle 8xe2x80x2 and the main nozzle 6xe2x80x2 are thereby avoided, because the tandem nozzle 8xe2x80x2 is now co-moved synchronously in rotationally fixed connection with the main nozzle 6xe2x80x2.
However, a massive problem results here in the change back to only one main nozzle 6xe2x80x2, or when the cloth width is to be reduced to such an extent that enough room for the positioning of the tandem nozzle 8xe2x80x2 and the main nozzle 6xe2x80x2 would be available on the sley profile 1xe2x80x2 even without the use of a longer sley profile 1xe2x80x2. A situation of this kind is shown in an exemplary manner in FIG. 3, with it naturally being possible for the tandem nozzle 8xe2x80x2 to be absent. Here the problem arises that undesirable additional masses must be co-moved. Enormous acceleration forces thereby arise through the pendulum-like movement of the sley profile during the weaving process which, if they are not to exceed certain limits, can make a reduction of the speed of rotation of the motor compulsory and/or can lead to the premature abrasion of corresponding machine components as a result of the additionally arising forces, for example in the form of bearing forces. Thus on the one hand the weft insertion performance is reduced and on the other hand maintenance intervals are shortened and the lifetime of mechanically stressed machine components is significantly reduced, through which the economical operation of the weaving machine is at least impaired. Moreover, additional thread guiding elements 9xe2x80x2 must be used on removal of the pre-nozzle from the unshortened sley profile for the guidance of the weft thread in order to prevent a collision of the weft thread with the sley profile (see FIG. 3). Additional thread deflection points with the corresponding negative frictional effects thereby arise.
It is therefore an object of the invention to propose an improved sley apparatus for weaving machines which permits alternatively the ideal use either of one main nozzle alone or of a main nozzle in combination with a further tandem nozzle which is executed as a pre-nozzle. The problems which are known from the prior art should be avoided in order to arrive at a solution which is on the whole technically and economically more advantageous.
In the sley apparatus satisfying this object the sley profile has at least two separate parts, namely a main profile part and an auxiliary profile part, with the auxiliary profile part being releasably connected directly or indirectly to the main profile part. A main nozzle is arranged on the main profile part, and a tandem nozzle is arranged on the auxiliary profile part.
The sley apparatus for a weaving machine in accordance with the invention has a sley profile, a reed and a drive, with the sley profile carrying the reed and being in active connection with the drive. In this the sley profile comprises at least two separate parts, namely a main profile part and an auxiliary profile part, with the auxiliary profile part being releasably connected directly or indirectly to the main profile part.
The step from the single nozzle variant to the combination of a main nozzle with a tandem nozzle as a pre-nozzle takes place in accordance with requirements, for example when, as a result of a greater cloth width or when caused by a specific yarn sort, only insufficient compressed air power can be supplied for an unobjectionable weft insertion at a given speed of rotation of the machine. In particular in the processing of weak yarns only a limited pressure level is possible, for which reason two nozzles which are placed one after the other are not only advantageous, but also necessary, for a careful loading of the yarn.
The sley apparatus in accordance with the invention eliminates the above-described disadvantages of the present prior art in that the sley profile comprises two separate parts, namely a main profile part and an auxiliary profile part which are directly or indirectly releasably connected to one another. Thus on the one hand through mounting the auxiliary profile part at the sley apparatus and through producing a direct or indirect rotationally fixed connection between the main profile part and the sley profile part it can be ensured that during the weaving process the main nozzle and the tandem nozzle are at rest relative to one another and undesirable thread deflection points can be avoided. On the other hand, when the tandem nozzle is not required in a given operating mode, not only the tandem nozzle but also the auxiliary profile part which carries it can be removed, so that no unnecessary masses of an unused region of the sley profile need be co-moved.
In the following the invention will be explained with reference to exemplary embodiments and with reference to the drawings.
FIGS. 1 to 3 show the prior art. To distinguish the prior art from the sley apparatus in accordance with the invention, the reference symbols in FIGS. 1 to 3 are provided with primes. dr
FIG. 1 shows a known embodiment for an arrangement of a combination of a stationary tandem nozzle and a main nozzle;
FIG. 2 shows a known embodiment for an arrangement of a tandem nozzle and a main nozzle on a sley profile which is made longer;
FIG. 3 shows as in FIG. 2, a region of the sley profile which is made longer remaining unused;
FIG. 4 shows an embodiment of a sley apparatus in accordance with the invention with a tandem nozzle and a main nozzle;
FIG. 5 shows a variant of the embodiment in accordance with FIG. 4;
FIG. 6 shows a further variant of the embodiment in accordance with FIG. 4;
FIG. 7 shows a further embodiment of a sley apparatus in accordance with the invention with an overlong main nozzle; and
FIG. 8 shows another further variant of the embodiment in accordance with FIG. 4.